From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
KVM needs to disable PEBS auto-reload for guest owned event to avoid
unnecessory drain_pebs() in host.
Expose a function to disable auto-reload mechanism by unset the related
flag. The function has to be invoked before event enabling, otherwise
there is no effect.
Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
---
arch/x86/events/intel/core.c | 14 ++++++++++++++
arch/x86/include/asm/perf_event.h | 2 ++
2 files changed, 16 insertions(+)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index ef95076..cd17601 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3299,6 +3299,20 @@ static int core_pmu_hw_config(struct perf_event *event)
return intel_pmu_bts_config(event);
}
+/*
+ * Disable PEBS auto-reload mechanism by unset the flag.
+ * The function has to be invoked before event enabling,
+ * otherwise there is no effect.
+ *
+ * Currently, it's used by KVM to disable PEBS auto-reload
+ * for guest owned event.
+ */
+void perf_x86_pmu_unset_auto_reload(struct perf_event *event)
+{
+ event->hw.flags &= ~PERF_X86_EVENT_AUTO_RELOAD;
+}
+EXPORT_SYMBOL_GPL(perf_x86_pmu_unset_auto_reload);
+
static int intel_pmu_hw_config(struct perf_event *event)
{
int ret = x86_pmu_hw_config(event);
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 29964b0..6179234 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -325,6 +325,7 @@ struct perf_guest_switch_msr {
extern void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap);
extern void perf_check_microcode(void);
extern int x86_perf_rdpmc_index(struct perf_event *event);
+extern void perf_x86_pmu_unset_auto_reload(struct perf_event *event);
#else
static inline void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
{
@@ -333,6 +334,7 @@ static inline void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
static inline void perf_events_lapic_init(void) { }
static inline void perf_check_microcode(void) { }
+static inline void perf_x86_pmu_unset_auto_reload(struct perf_event *event) { }
#endif
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
--
1.8.3.1
